1. Field of the Invention
The present invention relates to a solid-state image pickup device using a charge-coupled device.
2. Description of the Background Art
It has been required for a solid-state image pickup device mounted in a digital still camera or the like to address a demand for a reduction in size and weight, high reliability, high sensitivity, a high dynamic range, and further high resolution.
A conventional solid-state image pickup device disclosed in Japanese Laid-Open Patent Publications No. 2004-180284 and No. 2005-166826 will be described.
FIGS. 7A and 7B are diagrams illustrating the conventional solid-state image pickup device. More particularly, FIG. 7A is a schematic configuration diagram and FIG. 7B is a configuration diagram illustrating an arrangement of gates in a distribution transfer section 20 having a plurality of driving electrodes, which are provided independently in a column direction, for controlling readout of signal charges from an image pickup region 30 to a horizontal transfer section 10. FIG. 8 is a schematic diagram illustrating wiring in the distribution transfer section.
In FIG. 7A, the conventional solid-state image pickup device comprises a plurality of photo-detecting sections 50 which are disposed in a two-dimensional manner corresponding to pixels and in each of which any of filters of three colors such as red (R), green (G), and blue (B) is provided; and a CCD (Charge-Coupled Device) including driving electrodes V1 to V6, V3R, V3L, V5R, and V5L.
The conventional solid-state image pickup device further comprises a plurality of vertical transfer sections 40 for transferring in a vertical direction signal charges which are generated by the photo-detecting sections 50 in accordance with application of driving pulses φV1 to φV6, φV3R, φV3L, φV5R, and φV5L and driving electrodes H1 and H2.
The conventional solid-state image pickup device further comprises a horizontal transfer section 10 for transferring signal charges in a horizontal direction to an output amplifier 60 in accordance with driving pulses φH1 and φH2; and a distribution transfer section 20 which is disposed between the horizontal transfer section 10 and the image pickup region 30 having the plurality of photo-detecting sections 50 and the plurality of vertical transfer sections 40 disposed therein. The distribution transfer section 20 includes a plurality of driving electrodes, which are disposed independently in a column direction, for controlling readout of the signal charges from the image pickup region 30 to the horizontal transfer section 10.
In FIG. 7B, the vertical transfer sections 40 and the distribution transfer section 20 have a common pattern of electrodes for each 2n+1 (n is an integer equal to or greater than 1) columns and comprise driving electrodes V1 to V6, V3R, V3L, V5R, and V5L to which driving pulses φV1 to φV6, φV3R, φV3L, φV5R, and φV5L are applied.
The driving electrodes V1, V2, V4, and V6 are shared by all columns and the driving electrodes V3, V3R, V3L, V5R, and V5L are independent electrodes which are separated in an island-like manner for each column. The distribution transfer section 20 controls, independently for each column, readout of the signal charges from the vertical transfer sections 40 to the horizontal transfer section 10.
In FIG. 8, driving pulses are inputted via independent wires 110 to driving electrodes V3, V3R, V3L, V5, V5R, and V5L in the distribution transfer section 20.
In this case, in order to supply the driving pulses to the distribution transfer section 20, a total of six independent wires 110 are required for the independent electrodes V3, V3R, V3L, V5, V5R, and V5L. Three independent wires 110 extend in a horizontal direction in the image pickup region 30 and are connected to the driving electrodes V3, V3R, and V3L, and the other independent wires cross over the horizontal transfer section 10 and are connected to the driving electrodes V5, V5R, and V5L.
In the conventional solid-state image pickup device, the independent wires connected to the driving electrodes V5, V5R, and V5L are formed in an aluminum layer. In this case, the horizontal transfer section is light-shielded by a tungsten layer, leading to a problem of not obtaining a sufficient light shielding characteristic.